Lubricants are widely used to reduce friction between surfaces of moving parts and thereby reduce wear and prevent damage to such surfaces and parts. Lubricants are composed primarily of a base stock and one or more lubricant additives. The base stock may be a relatively high molecular weight hydrocarbon. In applications where there is a large amount of pressure applied to moving parts, lubricating compositions composed only of hydrocarbon base stock tend to fail and the parts become damaged. The lubricant manufacturer is in constant need to improve their formulations to address increased demands on fuel economy while balancing the need to reduce emissions. These demands force manufacturers to address their formulation capabilities and/or look for new base stocks that can meet the performance requirements.
To make lubricants, such as motor oils, transmission fluids, gear oils, industrial lubricating oils, metal working oils, etc., one starts with a lubricant grade of petroleum oil from a refinery, or a suitable polymerized petrochemical fluid. Into this base stock, small amounts of additive chemicals are blended therein to improve material properties and performance, such as enhancing lubricity, inhibiting wear and corrosion of metals, and retarding damage to the fluid from heat and oxidation. As such, various additives such as oxidation and corrosion inhibitors, dispersing agents, high pressure additives, anti-foaming agents, metal deactivators and other additives suitable for use in lubricant formulations, can be added in conventional effective quantities. It has long been known that synthetic esters can be used both as a base stock and as an additive in lubricants. By comparison with the less expensive, but environmentally less safe mineral oils, synthetic esters were mostly used as base oils in cases where the viscosity/temperature behavior was expected to meet stringent demands. The increasingly important issues of environmental acceptance and biodegradability are the drivers behind the desire for alternatives to mineral oil as a base stock in lubricating applications. Synthetic esters may be polyol esters, polyalphaolefins (PAO), and triglycerides found in natural oils. Of key importance to natural oil derived lubricants are physical properties, such as improved low temperature properties, improved viscosity at the full range of operating conditions, improved oxidative stability, and improved thermal stability. To address this, we have synthesized diester compositions with certain structural properties which address some or all of these physical properties.